演講資訊

摘要：

The assembly history of our Galaxy is encoded in the chemo-dynamical properties of its stellar populations. In this talk, I will present our work on AuriDESI, a set of mock catalogues generated from the Auriga cosmological MHD simulations of Milky Way-mass galaxies, designed to match the selection functions of the Dark Energy Spectroscopic Instrument (DESI) Milky Way Survey (MWS). I will discuss how these mock catalogues were used to understand how well a DESI-like survey can characterise the evolutionary history of a Milky Way-like galaxy. I will then discuss our work applying HDBSCAN, a density-based clustering algorithm, to 88,959 K-giant stars selected from three years of DESI MWS data to characterise the Galaxy's distant stellar halo. This identified the major structures in the stellar halo, such as the Gaia-Sausage-Enceladus, the Sagittarius stream, the Cetus-Palca stream, Aleph, and the Orphan-Chenab stream. Furthermore, we studied the metallicity distributions (MDFs) of prograde and retrograde stars with high angular momentum that are not assigned to any structure by HDBSCAN (i.e., the residual stellar halo), and found they exhibit a similar bimodal distribution, which does not resemble that of either Sagittarius or GSE. Based on these results, we discuss different GSE accretion scenarios, as well as future directions for characterising smaller, fainter stellar halo structures to improve our understanding of the Milky Way's evolutionary history.